Out doing some visual for a change last night with the binos (was too lazy to set up, despite the conditions being good - just dog tired!) when I glanced over toward the South West.
As I did so, the night was rendered with a blinding flash and a VERY loud explosion.
Now, I have not read any news about what it was, but my theory is acetylene balloon
Not a BIG one (I have seen, felt and heard - well, hearing stopped for a while - a LARGE acetylene balloon go off), but big enough to rattle the windows
Considering the farm land that stretches between us and Caloundra, I doubt anyone could ever be caught doing it.
Wife and 4 year old slept through the whole thing.