1. Water boils at 100°C at sea level. If the water in this experiment did not boil at 100°C, what could be the reason?

It may not be at the sea level

Explanation:

The reason here is water only boils at sea level. This means that if you move water to a different height, say top of a mountain, the boiling temperature of water would change. This is due to the pressure drop at high place. The drop of pressure would make it harder to transform water liquid to gas, thus requiring more temperature.