It is perfectly possible that a passenger in the back may not even notice anything untoward has happened,
Unless you are flying aerobatics and/or you have briefed your passenger appropriately that you are going to deliberately stall the aircraft, a stall should *not* happen with passengers on board.
A stall, even if it is a non-event, is a temporary departure from controlled flight. Normal practice is to perform all maneuvers so that a stall does not occur while doing them.
The reason stalls are taught during PPL training is NOT because you're going to need that skill during your normal flying sorties. It's because you're going to need your stall recovery skills in case you mess up something else first - speed control mostly.
In that sense, it's perfectly OK to dread stalling a bit - even after you've learned how to recover properly. That keeps you well away from that part of the envelope.
The best analogy I can come up with is skid/slip recovery during your drivers education. You get that not because skidding or slipping is a normal part of driving, but because you might need those skills in case you do something wrong, or something wrong happens to you.
(Strangely enough though, slipping may be part of your every day life as an aviator, depending a bit on the type of aircraft you're going to fly, and the best way to lose height or correct for a crosswind on final approach. And slipping is arguably less comfortable for your passengers than stalling.)