There is this boss in Auroria called King Honeygrave. If you get a raid you can get half a lvl of XP at lvl 15.
I am now lvl 21 and receive over 30% of a lvl every 6 mins (his spawn time).
As it seems every world boss now gives you sheitload of XP... just don't forget to mentor someone to get to the lowest lvl possible.
Enjoy
EDIT: there is already a post about world bosses giving too much XP so farm the hell out of em ppl... Shame I get like 4500ms with a full raid and can't do shit...