We have several lamps that were made to take tri-light bulbs. They can be clicked to low, medium, or high intensity. Two problems with this: tri-light bulbs are now hard to find and expensive, and a couple of those lamps needed repairs. The switch on our china lamp had suddenly stopped working, and one of the others turned out to be doing dangerous things inside its workings.
The china lamp has a new on-switch spliced into the cord.
And the bedroom lamp is no longer coming on without warning.
Moral of the story: stay safe and make sure your electricals are up to date.