Colligative properties systematically make the boiling point higher (ebullioscopy) and the freezing point lower (cryoscopy) as a function of the concentration.

In the more exact scheme, the activity instead of the concentration must be used. In order to lower the boiling point, you would have to have an activity below 0 and I've never heard of that.

Nour Mohamed

To increase the boiling point of water, it is necessary to increase the energy of the hydrogen bond between water molecules or to bind water molecules with ions, polar molecules. The term catalyst is used to speed up chemical reactions. You are not going to speed up the "reaction" of boiling water, but, on the contrary, to try to reduce its speed. Therefore, for this process it is better to talk about inhibiting the "reaction". The word reaction is in quotation marks, since this is not a reaction (during the reaction, the structure of the molecules changes), but a phase transition.

I would think that the only way to make the bp go down is to reduce the pressure. I don't know if any substance that makes it's bp go down, unless you are azeotroping it off (see for example the lists here: https://en.wikipedia.org/wiki/Azeotrope_tables

Most soluble things cause it's bp to go up due to colligative properties.

Kyle A. Grice Good point about azeotropes with another liquid, I only thought about dissolving a solvent.