So, there I was, taking advantage of the good weather here in the UK and going fishing with my best friend. Fortunately, Exeter Airport (EGTE) wasn't too far from the pond we were fishing in, so quite a few 'craft flew over. Sorry, no pics though

Anyway, as we sat waiting for a bite, we heard what sounded like a Cessna, only it kept on throttling up and throttling back down. Sure enough, over the treeline, came this Cessna 172, and it was indeed throttling up and going to idle. (I'm pretty sure it was on idle - I could still hear the engine running).

I thought "So, perhaps they're going out for a flying lesson and learning what happens if the engine fails".....but then again, I'd imagine they'ed have plenty of height for that. This little Cessna, however, seemed to be quite low. It then throttled up as the tail end of the aircraft dropped considerably - so what do you guys think happened? Perhaps the throttles were messing up, or could it have been a lesson?

EDIT: Sorry about the little story added to my question

Sounds like an approach gone wrong, with a go-around at the end... or yes, just stall practice.
Or a stuck throttle... it happens.