good answer.
i can attest that many RC benzos vaporize and smoke with heat, and they might well have even lower boiling points, hence the need for vacuum to boil at a lower temperature. that being said, i´ve definitely heated an empty but wet vial of benzo solution and smoked the contents well after the last of the PG disappeared from the surface of the glass, suggesting there was concentration of the benzo as a precipitate while the PG boiled off.
if you feel like experimenting keep in mind that PG will ignite in open flame; prolly not a good idea in a gas oven