The method that is used to obtain pure salt from a salt solution is
Crystallization
Crystallization is used to obtain pure salt crystals from salt solution. It is a separation technique that is used to separate a solid dissolved in a liquid. It occurs when the solvent of a saturated solution undergoes slow evaporation and gradually the solute begins to precipitate out of solution. In other words, the solute crystallizes.
Similarly, when saltwater beds are exposed to sunlight, salt crystals are formed as water slowly evaporates.