The Celta captain curled his freekick under the wall and into the back of the net to leave Marc-Andre ter Stegen helpless in goal.
"I knew where I was going to put it," Aspas said about the freekick after the game.
"We'd watched various videos with the goalkeeping coaches.
"I knew that they'd jump and I watched [the ball] go under them."
If it wasn't for Ter Stegen's late save to deny Nolito, Celta might have claimed all three points at Balaidos.
"We've taken eight from a possible 12 points," Aspas said.
"Taking points off Barcelona at our ground, we'd all have taken that at the start of the game but, seeing the last chance [for Nolito] and our final few minutes, you get the feeling we could've killed the game."