Sugar dissolves in water, right? Coffee drinkers know that and some who drink tea do too, but what happens if you put in more sugar than the water can hold? Place a few crystals of sugar on a microscope slide. Add a small drop of water and watch. If you are patient, you will see that at first the crystals dissolve rapidly, then the process slows and eventually seems to stop. As the water surrounding the sugar crystals hold more sugar molecules, the water becomes saturated. As molecules of sugar leave the surface of a crystal more molecules in the water return to the surface of the crystal. When the rates are equal, the water can hold no greater concentration and the crystals stop dissolving.
What if you put just one crystal into a drop of water? Or what if you added even more water to the saturated solution? To find out, watch the video.