Nether Portal

I was playing with my friend with a 100% Vanilla server. We didn't install mods.

I was in the nether gathering blackstone, basalt, and gold. I decided to go back to my house.
When I exit the portal it exploded, this happened on multiple occasions. I would think this was cool, if obsidian could be moved or exploded. I don't know if this is a change or a bug, but I haven't seen it anywhere else.