Water is a universal solvent and hence, it has many dissolved substances in it, mainly salts. In this video, we test 3 samples of water, namely, hard, tap and salt water; to find out which one has the most salts dissolved in it. A few drops of each of these water samples is subjected to heating on a metal plate. When the water is evaporated, it leaves behind the salt residues. We find that, salt water has the greatest amount of residue left, and tap water the least. Hence, the amount of dissolved salts is most in salt water, and least in tap water.