Heating the sugar/water solution increases the amount of sugar that can be dissolved. The heat caus- es the crystals to break into smaller molecules. The sugar molecules move faster and farther apart, enabling the solution to dissolve more and more sugar molecules. The solution turns into a clear sugar syrup. As you add more sugar, the solution becomes supersaturated. This means that the solution has reached a delicate balance of just enough sugar molecules and enough heat to keep the sugar molecules dissolved, but in an unstable state. The sugar molecules begin to crystallize back into a solid at the least disruption of heat or action. In other words, the sugar comes back together as sugar crystals when the syrup cools.