This video shows what looks like regular sand - but it's quite different going into and out of water. You can make this sand by spraying sand with Scotch Guard.
A visualization from NOAA that shows what the earth would look like if all water drained out. Good to show so students can see the mid-ocean ridges, ring of fire boundary, etc.
i tried this demo for the first time this year. It didn't work perfectly but it really gave the students a visual of the formation of minerals. I would suggest marking the water level on the jar when you first set it up so they can really grasp how much has evaporated by the end. I let mine sit for almost 3 weeks but crystals were forming within 3 days.
This is an activity I use as a visual for the students to see the different types of pollution that affect rivers. I modify it by talking about the MO river.