Depending on your level and contribution (As in Last Hitters who may try to retroactively try to get a smack too leech EXP, fuck off), this is how much EXP you'd get from the boss:

Level 5 Dissolution Boss: Level(5) x 100 = 500

NC System bonus:
Level 4 = 750 (+ 1/2)
Level 3 = 1000 (x2)
Level 2 = 1500 (x3)
Level 1 = 1500 (X3)

EXP needed for leveling up:

Level 2 – 10,000 EXP
Level 3 – 20,000 EXP
Level 4 – 40,000 EXP

So unless you were already at the verge of leveling up, no, this boss isn't going to give you enough to level up.