* Cobalt chloride's color change: Cobalt chloride is a hygroscopic substance, meaning it readily absorbs moisture from the air. When anhydrous (without water), it's blue. As it absorbs water, it forms a hydrated complex, which is pink.

* Boiling point of water: Water has a boiling point of 100 degrees Celsius (212 degrees Fahrenheit) at standard atmospheric pressure.

Therefore, the presence of water (which turns blue cobalt chloride pink and has a boiling point of 100 degrees) is the key to this chemical change.