Amanda,
If you're talking about the action of sliding your foot off the side of the brake pedal and allowing it to spring back to it's initial position on it's own, then yes, most cars have a clunk or pop, as you say.
This is because there is a stop that the pedal comes to rest against. That stop is supposed to have a rubber sleeve or cover on it. If you find yours missing, you could probably measure what you need and find something in a hardware store that would work. I don't know if the actual MB part is still available.
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420