Effervescent fuel
Found this to be interesting. Some aircraft have a max altitude without boost pump capability, some don't. Pehaps due to effervescence.
Jet fuel contains dissolved air and the amount depends on the temperature of the fuel and the altitude. As the airplane climbs to cruising altitude, and the ambient pressure decreases, air is liberated from the fuel as bubbles that rise to the surface. As the flight progresses the rate of effervescence decreases as the fuel comes into equilibrium with the atmospheric and fuel temperature conditions. This condition is called fuel weathering.