Y does milk rise to surface of vessel when boiled while water doesnt???

Question

Y does milk rise to surface of vessel when boiled while water doesnt???

Answer 1

Heated water also rises to the surface but it can;t be seen because water is water, but milk contains solids, they thicken and rise to the top as cream.

Answer 2

The fat in the milk solidifies into a thin film on the surface of milk vessel. Air trapped inside has no escape so it lifts that film up. you break that film or puncture it, the milk will not boil over till another layer is formed.

Answer 3

Milk is thicker than water, the cream in the milk thickens when it is heated to higher temperature and tries to expand