Why does boiling milk overflow bur boiling water does not?
Milk has more solid particles suspended in it that water. These solid particles hold the liquid together better. When something boils, the boiling is water that has turned into a gas. Since you heat a pot from the bottom, the gas is created on the bottom. The gas then bubbles up. If you were to heat it from the top, the water would never boil. With water, there is a very weak bond and the bubbles break easily, but since there are many particles suspended in the milk, the bubbles do not pop easily and the bubbles will push each other up and over the side.
