A machine gun with a pop in one of the rooms was knocked out, but found no malfunctions

Guys, please help me resolve the issue. They heard cotton in the next room, as if a small balloon had burst. Having examined the room, I did not find anything. I turned on the light, checked the sockets, everything works. In the morning, being already in this room, the cotton repeated. But there was already a slight smell of the prisoner and the light was cut off. There is a power outlet in the room, a night light and a power strip are connected to it. I connected the clock to a power outlet in another room, everything works fine. I disassembled the socket, everything is fine. I didn’t find anything singed. I turned on the machine and everything works well. It’s not clear to me. It would be a circuit, automatic machines would be cut down constantly. The clock works, sockets too. What is it?