Dissappearing brakes

[Cableguy]

After Losing brakes on my last trip due to a failed servo hose.
Coming back from a trip yesterday involving lots of roundabouts and generally lots of braking, the pedal seemed to get lower to the floor. Then suddenly, straight to the carpet. Carried on going very slowly on a long stretch with no braking and after a while, a good 15 mins, the pedal came back up.
After Reading here, I'm thinking boiling brake fluid??
Does that sound a possibility?

[BOXY]

Sounds likely. If you pump the brake pedal you should get some feel back straight away if the fluid is boiling. If pumping the pedal doesn't make a difference the seal in the master cylinder might have failed? The recommendation is to change the fluid every two years so getting that done can't do any harm.

[Cableguy]

Thanks for that, Just hope the bleed nipples are in good nick!!