The first time I experienced this was last year at DemocracyFest. I called it a "Polarity Burst." This is historic footage. Watch as the Internal Coherence Frequency (on the left) shifts quickly and goes off the scale twice.
Something went wrong while recording this and it came out in fast forward with no sound. At normal speed, these Polarity Bursts lasted a total of 12 seconds. The feeling was awesome!