why does milk overflow when boiled but water does not ?

Answer 1

milk more readily boils over because of the fat solids in it. They expand from heat so the fluid spills over the container it is in.
Water can do this also, but not as readily as water contains no fat solids.

Answer 2

Good question. The answer of KC is absolutely correct. Milk contains about 5-7% emulsified fat which on heating forms a layer on top and it prevents water vapours to escape hence the steam pressure is formed underneath. This steam pressure pushes up the layer of fat and baubles of milk, hence milk overflows. While, in case of water, steam is easily able to escape on boiling, hence there is no overflowing. I hope you will be satisfied. Keep questioning. Wish you all the best.

Answer 3

When water boils, you have at the interface the transformation of liquid water to gaseous water, whereas with the milk you have a film of milk protein formed at the interface. The continued build-up of water (in gaseous form) or steam continues as more heat is applied and the steam breaks through the bubble formed by the milk protein.

Answer 4

If the amount of water is more than the pots capacity it will overflow. Water does not overflow as much because it loses a lot through evaporation.

Answer 5

I don't know what kind of water you're using but I've had it boil over! It doesn't make the mess that milk makes, but it's still a nuisance.

Answer 6

Who says water doesn't boil over?

Answer 7

Water will too but it's evaporation point is less then milks.

Answer 8

Because they have different chemical compounds that respond differently to heat.