Comment by Eisenstein

> If the steam condenses to water (for example due to raising its boiling point above the autoclave's temperature of ~125°C) that'd probably be bad

If water boils at 100C then steam condenses at 99C. If water boils at 120C then steam condenses at 119C.

> higher-than-atmospheric atmospheric pressure.

What does that mean?

> I don't see an explanation that fits all the mentioned facts

Is it really a difficult concept? If the boiling point rises so does the condensation point.