What happens when milk boils?

Answer 1

Milk boils out because -

Milk is a colloid that has many substances suspended in it such as protein, sugar and fat. When milk is heated slowly the proteins and fat get separated. Since protein and fat are light they rise to the surface of the milk and collect together in the form of cream.

Milk has a high content of water in it and when the milk is heated some of the water gets converted into vapor. Since the surface of the milk is covered by cream the vapor gets trapped below the cream layer.

As the milk is heated the trapped water vapor expands and pushes against the layer of cream. The cream layer is lifted up as the water vapor expands and finally the pressure of the water vapor bursts through the cream layer and when this happens milk boils over and spills out.

Water does not boil and spill out because -

When water boils, bubbles form at the surface of water and burst. For water bubbles to expand further the temperature must be high enough so that the vapor pressure exceeds the atmospheric pressure or else the water vapor bubbles shrink and vanish.

Answer 2

Milk is thicker than water, the cream in the milk thickens when it is heated. Water has no property in it to thicken.

Answer 3

it turns into cottage cheese...no joke....nnnahh...its starts to boil and then pops around and if you try to drink it its like drinking tapitio.....it wil burn for a month :O

Answer 4

Here`s a part from the answer: http://www.pitara.com/discover/5wh/online.asp?story=124 . After you read this you`ll see why the water doesn`t spill over on boiling.