30k+ EXP comes from the mob vs pet and mob vs player average levels.

Say you're fighting beetles. their average level is about 24. If you have a pet level 1 and your level is 54+ you would get a significantly higher amount of Experience than if your pet was level 6-10. While solo bursting I usually hunt for a new pet once it reaches level 10-11.

1 beetle with level 1 pet and decent combo gets me about 2k exp.
1 beetle with level 10 pet and decent combo gets me about 500 exp.

My main fire character is level 68.