There is a company - Evans Cooling - that has a "non-aqueous" coolant on the market. It is pretty expensive - but interesting anyway...www.evancooling.com
This liquid coolant is not water based - and it has a boiling point of 370°F. Because it doesn't boil at common automotive cooling system temperatures, the pressurized system we all know and love is not a part of their cooling scheme. The system must be closed and have an overflow return for thermal expansion reasons - but suppressing the boiling point isn't the reason for the low pressure cap.
According to the company write-up / literature, the principle operational advantage is that the coolant exposed to the heated surfaces of the engine never flashes to steam, which they say limits the effective cooling by "insulating" the exposed surfaces with bubbles. The new coolant supposedly stays in a more effective heat transfer state.
Anyone have personal knowledge of this stuff?