The children added water and is poured into this foil container, and a small amount of salt is added. When the candle is lit and placed beneath the tinfoil, it provides heat energy to the solution. As the water warms, its molecules move more rapidly, which helps break apart the salt crystals into individual ions that disperse evenly throughout the liquid. This process is called dissolving, and heating speeds it up by increasing molecular motion and the rate at which the salt interacts with the water.