Why pans boil over

Oh no, it happend again.

It only takes a few seconds of distraction, and then it happens: your saucepan suddenly boils over. The cooking water flows over the cooker top in a flash, often leaving unsightly marks.

Unlike milk or water used to cook pasta, rice or potatoes, pure water – for tea, for instance – never boils over. So why does this often happen with pasta water or milk? The explanation is really quite simple. What’s more, there are even some tricks that you can use to avoid having to scrub your cooker top yet again.

An overcooked pot on a BLANCO stainless steel sink

Why pans boil over

When you boil water, after a while you’ll notice that more and more bubbles are rising to the surface, only to burst immediately. Water boils at 100 degrees Celsius, but it doesn’t boil over. The reason why this tends to happen with milk or pasta water is perfectly logical and straightforward. When pasta, rice, potatoes or pulses are cooked in it, the water has a higher starch content. For milk, meanwhile, it’s the protein that makes it boil over. Coagulated protein and starch stabilise the bubbles of gas that occur in the boiling process. These cannot burst immediately, thus allowing foam to build up quickly. The volume of liquid multiplies and bubbles out of the pan. On gas stoves this can extinguish the flame, while largely empty pans left on electric stoves can overheat. One thing is the true of all types of stove: this mishap leaves unsightly marks on the cooker top, and you’re at risk of burning yourself if you start scrubbing at them vigorously.

Cleaning tips for after a pan has boiled over

Dried milk can be scraped off ceramic hobs using a ceramic cooktop scraper. Any remaining marks are best removed with a power cleaner. If you don’t have a ceramic hob, you can remove the marks with a few squirts of vinegar or a standard cleaner. Of course, you can also use special oven cleaners for this purpose

If the marks prove particularly stubborn, you can deploy an effective trick to combat them. Mix roughly a quarter of a dishwasher tablet with a little water in an eggcup. This should give you a slightly grainy pulp. Pre-heat the oven gently, then turn it off and apply the mixture over the affected areas. Leave the cleaner to do its work for 24 hours. Finally, remove any residue with a simple surface cleaner. All done!.

A man puts pasta in a high pot, it's on the stove.

Preventing overboiling

Often you simply don’t have the time and even less inclination to clean up pasta water or milk that has boiled over. What’s more, your cooker top can really suffer as a result. That’s why you should prevent it from happening altogether. The fact is that you could keep a watchful eye on the pan for minutes, but it only takes a second of inattention and the wrong moment, and the next thing you know you’re scrubbing the cooker again.

Luckily, we have a few useful tricks.

To reduce the amount of foam that builds up, drop a little butter or vegetable oil into the water before it boils. The oil will then combine with the starch and reduce the amount of froth. In pasta water, this prevents the pan from boiling over, but it can also prevent the sauce from sticking to the pasta quite as well, as it’s now oily. As such, it’s better to simply use your very biggest pan.
Another trick that uses butter: brush a little over the upper edge of the pan to prevent it from bubbling over.
Putting a lid on, meanwhile, is less hassle but is more likely to result in the pan boiling over. If you don’t want to do without a lid, however, make sure you use one that doesn’t slide around. If it does move, lift it briefly to allow the accumulated heat to dissipate.
The easiest thing is to stay close to the pan and give it an occasional stir. This disturbs the bubbles, while also preventing burning.
Ultimately, liquids boil over due to their chemical components. Just following one of these ‘life hacks’ can spare you from having to wipe up milk or pasta water.

Many people see washing up as a tiresome chore. Fortunately, dishwashers are now a standard feature of almost every kitchen. They make the perfect household aid and make your day-to-day tasks that bit easier. Thanks to their low water and energy consumption, most dishwashers are actually even more economical and environmentally friendly than washing up by hand. But not everything can or should be cleaned in a dishwasher.