If you want to increase the boiling point then have more antifreeze in there. But, think about why would you want to increase the boiling point. If that was your only goal you could put just sand in the radiator.

The key is heat transfer - out of the engine and out of the radiator. Pure water is pretty much THE best heat transfer fluid. Thus, in theory you should run pure water. In the real world you have to worry about corrosion, water pump seals, and freezing. Thus, the development of antifreeze with corrosion resistance and water pump lube chemicals.

Bottom line - antifreeze is good for some things. But too much is not your friend when it comes to keeping the vehicle cooled.