The solidification of salt water

What is the difference between physical and chemical transformations ?

During chemical transformations, substances change into other substances, which is not the case during physical transformations.

Is freezing a physical or chemical transformation?

It is a physical transformation.

What do you notice during freezing of salt water?

During freezing temperature increases.

Why?

A mixture like salt water is constituted of different kind of molecules. They behave differently, for instance in this case, freezing temperature is not constant!