Milk in a regular pan:

The surface rises more than 2" (50 mm) after a while...

Milk in a geyser pan:

The surface stays calm enough all the time.

Pasta in a geyser pan:

The surface stays almost calm all the time.

Vegetables in a geyser pan:

The surface stays almost calm all the time (except the waves from the vegetables).

Vegetables in a geyser pan with milk:

The surface doesn´t raise much more than 0.5" (12 mm) and stays almost calm all the time (except the waves from the vegetables).