Another way to supercool water is to keep adding ice to a saltwater bath. In this bath, you float another container (in lab, a beaker) which has non-salinated water in it. If you stir this water pretty much constantly while adding ice to the bath, it will go below the temperature of 0C or 32F (freezing point). If one measures the temperature of the water during this process, it has interesting trends. The temperature will drop steadily, even passing below the freezing point, as mentioned. However, as soon as you stop stirring, the temperature will spike back up to the freezing point and the water will begin to crystallize. Now, if you start stirring again, the temperature will go back down again, and spike up repeatedly, as before. This information comes courtesy of a first-hand general chemistry lab. (Oh yeah, and you can try this at home.)