Salt can be separated from a salt water solution by evaporation. All one needs to do is to heat the water to a temperature equal to or more than its boiling point. This will cause all the water to evaporate, leaving behind only salt. This can be tested in a lab using a Bunsen burner or at home using cooking stove or in your backyard.
The salt that we eat used to be made (and sometimes is still made) by evaporation of sea water (which is very salty). The sea water would be filled in shallow trenches near shore and left for some time (even days, depending on the regional temperature). Sun's heat will cause water to evaporate, leaving behind salt crystals, which would be further processed to yield salt.
Hope this helps.