Salt and Water Science Experiment

Our question was "what happens when we keep adding salt to water"?

Texas mixing salt in water

Answer: If we keep adding salt to water, after a while the salt doesn't dissolve in water because all the space in the water has been filled so any extra salt just sits at the bottom of the glass.

Then came the question of how do we know that the salt is still there?  

To answer this question, we left the salted water in the sun, over the weekend and when we came back on Tuesday (Monday was a holiday), most of the water was gone (evaporated) and we were left with a salt rim.

The rim of salt