"Although the video is somewhat grainy, the fact that they burst outward, rather than inward, would seem to suggest that the inciting force wasn’t a pebble or o

"Although the video is somewhat grainy, the fact that they burst outward, rather than inward, would seem to suggest that the inciting force wasn’t a pebble or other object striking the window from outside." That is actually not true with vehicle windows. They often are tempered and layered so they usually pop back with the force of getting something hit and blast out. Not saying this isn't spontaneous but my experience with car windows breaking is most of the glass ends up on the outside when struck from the outside.