Pressure is what raises the boiling point, not the glycol. That is an antifreeze, not an anti-boil.
Note that at 2Atm (~28psi), the boiling temp has increased to 120 deg C (248deg F).
The best cooling you get is with straight water + water wetter. But, you lose the corrosion protection. Out here in Phoenix (if my car never left the area), I'd run a real small amount of anti-freeze in my coolant mix, just to get the corrosion resistance. In places where it get cold, I'd run a 50/50 mix (or whatever it indicates on the bottle).
I don't think I'd ever run straight antifreeze as you'll lose a lot of cooling capacity that way. Water can hold a lot more heat than gycol.