Sascha notices that it takes a long time for a pot of water to reach the boiling point. what property of water is she observing?

Specific heat capacity of water

Explanation:

Water possess a very high specific heat capacity which means that the amount of heat energy required to boil 1 liter of volume after reaching a certain temperature which is 100 degree celsius in case of water. therefore the heat energy requirement or the temperature at which water boil for a given volume of water is extremely high.

Hence, the long time taken water in pot to reach the boiling point is the time required to reach the temperature at which water boil.