I believe another post implied you could increase the temperature of boiling water by boiling it longer. This is not the case. The altitude (air pressure) determines the boiling temperature.
Once boiling, water will not get hotter, no matter how much heat is added. Adding more heat just makes it boil faster. This is the nature of first-order phase transitions, where e.g. water (liquid) is converted to steam (gas). Such transitions involve the "latent heat of evaporation" of the material, water in this case.
This means that heat is needed to convert liquid to gas at a constant temperature, and all heat added goes into converting more liquid to gas, and does not increase the temperature.
Once all the liquid is converted to gas, then the temperature of the steam can be increased by adding more heat. This is done e.g. in closed steam heating systems, power plants, etc.