"The teacher is very boring."
Translation:Læreren er svært kjedelig.
"Læreren er kjempe kjedelig"
This is not accepted. My Norwegian wife says that she would translate that as "very boring" but maybe the issue is that others would translate it as "pretty boring"?
Kjemepekjedelig (no space) is VERY boring, but not something you would use much in writing if you are older than 30. It is used more in informal spoken language. Very would often translate to veldig.
To me "svært" is a bit more formal, but they're otherwise interchangeable in meaning. Some may see "svært" as a bit stronger than "veldig". I can't really think of a situation where either of them would feel out of place, so you're pretty safe regardless of which you choose.
Beware that "svært" is also the neuter form of the adjective "svær", which means "big" or "huge".