When you dissolve a solid (like sugar or salt) into boiling water, the heat allows the water to hold much more of that substance than it normally could at room temperature. As the water cools or evaporates, it can no longer hold all that dissolved material. The "extra" molecules are forced out of the liquid state and begin to latch onto one another, forming a highly organized, repeating geometric pattern—a crystal. What You’ll Need Before you start, gather these basic supplies: