random large pustule on my leg that popped the second i touched it

as i was getting in the shower, i noticed a large pustule on my leg. it grew to a pretty large size and burst the moment i touched it, but nothing was there this morning. it hasn't hurt at any point today, but it's weird how quickly it showed up, grew, and burst. anything to be concerned about? the big ones in the third picture is what it looked like before it popped.