Answer: You can apply the fact that water changes from liquid to gas when heated to its boiling point.
Step-by-step explanation:
Salt solution contains salt dissolved in water. The water can be separated from the salt by evaporation of the solution to dryness. This exploits the fact that water changes from liquid to gas at it's boiling point. This is an example of change of state. When heated strongly, all the water present will be converted to vapour and the solid salt reappears.