Some time ago I spontaneously ‘backed’ out of a dream and found myself in an utterly unfamiliar dreamspace.
I found myself weightlessly floating in a seated position (but without any chair) with my elbows at my sides and my forearms parallel to my thighs. My body perception was flooded with a kind of electric sensation – a not unpleasant tingling – and I started to rotate forward until I was tilted more-or-less downwards. There were no accompanying visuals or sounds, just pure bodily sensation. After a few moments I came awake.
I have been able to repeat this maneuver several times by reminding myself to back out of a dream.
Note; this ‘backing out’ consists of withdrawing precisely backwards, like pulling a piece out of a jigsaw puzzle, and happens very abruptly, with no transition from the dream to the ‘behind space’.

Please let me know if any of you dreamers out there have experienced something like this.