Éclater normally means “to burst”, “to break”, “to shatter”. S’éclater is a useful colloquial word with a different meaning: to have a lot of fun.
On s’est éclatés à la soirée du Nouvel An.
We had a lot of fun at the New Year party.
Il s’éclate dans son travail.
He really enjoys his job.
It is also possible, although less common, to use éclater with the subject being the thing you enjoy.
Il m’éclate toujours autant, ce film.
This movie still makes me have a lot of fun.
Ça t’éclate, de faire pleurer les filles ?
Do you enjoy making girls cry?
Listen to the examples: