As long as the water is kept at that temperature, all the sugar remains in solution. Now cool the sugar water. Pass the water containing dissolved sugar through a coffee filter. By taste, compare some filtered sugar water with unfiltered sugar water. You might try some of the above activities with salt.
Suspension Get some river water from a silty river.
Let the water sit overnight. Stir it up again. Let it settle. Heat the water in a clear container and keep it heated with an alcohol lamp or other heat source. Let the silt settle.