Preventing Milk from boiling over.

Milk is one of the most insidious liquids while cooking it. Not only does it boil over quickly, it also leaves  stubborn residues when it burns - My grandma was always  annoyed about this. The reason for this is that the milk proteins spread like a net over the entire surface of the milk in the pot. When the air bubbles rise from below they create pressure against this net, foam is formed that will swell up further and further causing the milk to boil over. The following trick will prevent milk from boiling over . Take a piece of Butter thinly spread it on the top edge inside of the pot. IT prevents the direct contact of the milk foam with the rim of the pot, the gases can escape and do not push the foam upwards thus preventing the milk to boil over.