Why do you think the warmer water at the bottom of the top rises to the top?

When you heat up water, the water molecules start moving around faster and faster. ... So hot water is less dense than cold water. When you put the two together with the hot water on the bottom, the hot water rises to the top, mixing with the cold water along the way and creating purple water.

Iwould you figure it out but you don't have a picture or in your question as to what the physical property you're looking for is