This came to my mind last night. When I was about three, I recall an instance where someone (either my mother or grandma) plugged in an appliance in our basement and turned it on just as I was coming down the stairs. When that happened, two light bulbs in the room next to the stairs, which had an opening in the wall so you could see the room from the stairs, emitted a blue flash, even though they weren't turned on. I know this is an arc flash but what could have caused it under those circumstances, especially with the lights not even on?

Some mess in the wiring there (causing brief overvoltage by effectivrly connecting them across the 240V; something involving broken Neutral,...)?

It may also be a reconstructed memory from different experiences, including a bulb that blew out. I know this memory is clear in your mind, but you were three and even memories that a few years, weeks, days old are reconstructed. Our brain does it all the time.