doppeldecker, you are being led astray by frankly some of the craziest answers I´ve ever seen! It´s an unfortunate fact that the people who don´t know tend to answer first in Pprune.
A jet engine surge or stall is caused by the pressure build up through the engine reaching excessive levels. There are bleed and pressure relief valves in the engine to bleed-off excessive pressure. If, for some reason, the pressure behind a stage of compressor blades versus the pressure in front, reaches an excessive level, the pressure will surge forwards like a 'cough'. It can sound like a canon shot, and at night it looks spectacular with sparks and smoke 'coughing´out of the front of the engine. It lasts a fraction of a second and then often recovers. But sometimes the gas temperature and burning of fuel gets so disrupted that the engine will start overtemperaturing. The blades are not 'stalling'! When that happens, you are really into a problem with the engine.
Some of those early answers are really off the wall! Post 2 belongs in a lunatic asylum!