Season 8 of "The Big Bang Theory" will end with a big bang as both couples on the show will reach major milestones.

A preview video of Thursday's season finale, "The Commitment Determination," reveals Sheldon and Amy will share an intense kiss. In addition, Leonard and Penny will seriously considering eloping in Las Vegas.

Executive producer Steve Molaro also dropped spoilers about the finale, revealing that Amy will become frustrated with her slow-moving five-year relationship with Sheldon and present him with an ultimatum.

"She's fed up with how slow their relationship is progressing over the past five years," Molaro told The Hollywood Reporter. "So she puts him up against a wall and says, 'What are we doing?'"

In response, Sheldon points out that it's been over a year since Leonard and Penny got engaged, yet they have no set wedding date in order to divert some of the pressure.

"He goes, 'You two haven't picked a wedding date yet. Why not?' So that comes to a head, too," said Molaro.

"It has been five years, and even though things have been progressing, for Amy, it's still, for her, not quite at the speed she'd like, so she really starts pushing back, and he's got relationships on his mind because of that," Molaro told THR. "He wants to know why he's getting grief about moving slowly, where if Leonard and Penny are an example of a couple moving forward, they've been engaged for over a year and can't even pick a date. So he starts poking at that and making them ask themselves the same questions. Both of those couples -- Sheldon and Amy and Leonard and Penny -- make some huge, life-changing decisions."

This will also force the engaged couple to confront the truth behind their non-existent wedding date.

"Penny and Leonard would tell you the reason is she's busy with her new career and things are really great between them and they're in no rush," explained the EP to TVLine. "But, underneath it all, what's the real reason? That all comes out. The show has always been Leonard and Sheldon, our single bachelors living in that apartment," reasons Molaro. "But we're going right into the heart of that at the end of the season."

According to The Hollywood Hills, the synopsis reads as follows:

"Sheldon (Jim Parsons) is going to push Leonard (Johnny Galecki) and Penny (Kaley Cuoco-Sweeting) to choose a date for their wedding and will deal with dramatic changes in his own relationship with Amy (Mayim Bialik)."

Season 8, Episode 24 of "The Big Bang Theory," " The Commitment Determination," will air on Thursday, May 7 on CBS.

Watch a preview below.