A reality bubble was a kind of technology.
Jake Morgan was accidentally caught in a reality bubble when Jeremy Fitzoliver messed with the Third Doctor's TARDIS controls. Jake was unable to interact with the outside world, and thought he was dead. He was then brought into the Time Vortex by the Doctor, as he was unable to free Jake from the bubble. (PROSE: The Dead Man's Story)
Gallifrey continued to exist at the exact end of the universe with part of the Cloisters still being intact and used by Me to watch the end of everything, preserved by a reality bubble. After Me discussed the Hybrid with the Twelfth Doctor, the two left in the TARDIS he had acquired, after which the reality bubble gave out and the universe finally ended. (TV: Hell Bent)