These are not so spectacular:
A couple years ago in a restaurant with many hanging pendant lights around many tables (it looked like 1960's style), I noticed one of the bulbs near my table was "acting funny". I recognized it. So the next time I got the attention of the waiter, I told her that (pointed to it) bulb was burned out. She, of course, was confused because it was still lit. So I just added to what I said with "it looks like it burned out about three minutes ago" (thus much I simpler made up ... I really didn't know). So she finally said "but it's still on". So I said "sure, but when a bulb burns out, it often stays lit until the next time it is switched off and back on". So she switched it off and back on, and it did not light back up. I probably had her puzzled all day.
My bathroom has a one of those light sensor controlled night lights. For certain things I do in there, that is all the light I need, so I often do not turn on the main light. I started noticing the light looked brighter than usual, and had a flicker to it. Yet it would keep coming back on as I flipped the main light on and off. Eventually I decided to take a closer look and found that part of the long filament (4 watts 120 volts) had broken and fallen against a support wire of another segment, completing the circuit but with less filament length. I just went ahead and replaced it right then.