Want to make crystal snowflakes but without the borax for the younger folk? Try this (slightly different, but still cool) version.
What's Going On?
Dissolving salt in hot water is different from dissolving it in room temperature or cold water; since water molecules in boiling water move faster and more freely, there is more space for the salt to dissolve.
As the salt water loses heat, these water molecules slow down and are more close together. It can no longer hold the amount of solution that it could when the water was boiling. This is what causes the crystals to form on the snowflake!