They sound to me like sonic booms.
I live near an AFB and we get them regularly. A big boom, shakes the house (scares the sh!t out of you cause you don't expect it)
I used to think it was a crash on the highway in front of my house. I bet I looked a dozen times and nothing.
I finally realized what it was, sonic BOOM!
Testing military tech? At night so no one sees? I can't go with aliens sorry
Except that in many cases . . . there is not a plane in the sky from horizon to horizon and further.
[What do you think the booms/explosions are?]
There has been a lot of seismic activity throughout the world this year.
https://earthquake.usgs.gov/learn/topics/booms.php