What happens to liquids when they get hot?
They turn into vapors/ gaseous state.
Take Water as an example. Upon heating it, it changes its state into vapor form. The reason behind this is the inter-molecular spaces and forces.
Liquids have less spaces as compared to gases .
Upon heating, the molecules gain Kinetic energy and start striking with each other at full force. This causes the molecules to move further away from each other.
As a result the inter-molecular forces weaken and the spaces increase.
Increase in inter molecular spaces means increase in volume of the substance and increase in volume means decrease in density as:
and this means that density and volume have an inverse relation.
As the volume increases and density decreases, liquids change their state and turn into gases.