I have certainly had what fits the OP's definition of spontaneous experiences one a few occasions. One, oddly enough was actually partly confirmed after the fact. Always from a sleeping state too. I have actually had a few really neat experiences, but sadly I don't tend to consider them true successes. I have never projected with full intention and and from a non-dreaming state. A fully conscious remains a goal of mine, but I do see a link between intending to do so, an openness to the idea and a tendency to project spontaneously from dreams, ect. By trying to do so, consciously or not, we certainly gave our minds a great suggestion and surely the mind is happy to take us up on it. It;s my belief that the human consciousness wants to do such things anyway, and if we basically give it permission, well them of course off it goes.