Just running "dreamed" and "dreamt" past my internal editor (inside my brain) and it suggests "perfect" for the first and "pluperfect" for the second.

It says it gets a feeling that "dreamed" is something in the past but in the middle past, while "dreamt" is in the distant and inaccessible past ...

... in Latin class we were told the past tenses were

imperfect - I was dreaming
perfect - I have been dreaming (?I dreamed?)
pluperfect - I had been dreaming (?I dreamt?)

There is certainly a hint of distance in the "I dreamt of far away lands and never dreamed that one day I would visit them".

Also, as may have been said by someone else, "smelled" feels like it is an action while smelt is more of a state.

E.g "the fire burned all night but the sausages did not get any more burnt"

In many cases "dreamt", "burnt", "learnt" are nouns or adjectives (the burnt sausage, the learnt phrased (and always a learn-ed expression, never a learnt one).

And sometimes it's how it fits into the rest of the sentence
e.g.
"the house was burnt" vs "the house burned all night"
"the lesson was learnt" vs "the lesson was learned by the class"