Evaporation: Separating a soluble solid from a liquid.
If you have a solution and you separate it because you need the solid, then evaporation is the technique you will need to use. Using heat will speed up the process, but evaporation works by allowing the liquid to change into a gas leaving the dissolved solid behind.
These are salt pans in Malta and Portugal. Sea water is pumped into the pans. When the water evaporates, the salt is left behind which is cleaned and sold for us to use on our fish and chips!
The Danakil region of Ethiopia is one of the most hostile places to live on Earth. It does not rain and daytime temperatures can reach 50 degrees Celcius. However, peolpe have lived there for millions of years - the famous fossil Lucy was found in the region. The region is also 100 metres below sea level.
But... people have been mining salt here for centuries. The lake has a very high salt content and as the water evaporated, masses of salt was left behind. The local Afar tribe carve out salt by hand, pack it onto camels and take it to town which is a weeks walk away.
Read more about the area: