Bright light moving quickly before blinking out of existence.

I looked to my left (east) and high in the sky moving quickly to the north was a very bright light.  I saw it move extremely fast northbound before it turned back on itself on the same plane, just for a tenth of a second, then stopped and blinked out of existence.  As it disappeared it brightened up before looking like it collapsed instantaneously in on itself into a horizontal line of light.  Working as a lighting tech on movies, I know how different lights appear under different conditions and optical circumstances.
Under ordinary circumstances, we would explore whether the witness might have observed the "flare" of an "Iridium" satellite.  However, satellites do not reverse their course.  PD