The Big Bang Theory Season 6 finale served a major breakthrough involving Kunal Nayyar's Rajesh Koothrappali. There is no science discovery involved, but it is massive and it changes the dynamics of the show.

Spoiler Alert: This feature contains spoilers for those who have not seen "The Big Bang Theory" Season 6 finale, "The Bon Voyage Reaction."

Grieving over the end of his first serious relationship, Raj finds himself opening up to Penny. His socially awkward soulmate Lucy (Kate Micucci) breaks up with him just when he though they're both in a great adventure.

It would have been ordinary. Penny is the one person who can comfort Raj when he's depressed. Remember The Big Bang Theory Season 4 finale? Well, that's a different story. This time, in a surprise character development, Raj is talking to Penny without alcohol in his system!

"It's really wonderful because after playing this character for six years, you see him slowly let his guard down," Nayyar told The Hollywood Reporter. "In sitcoms, you can sometimes get stuck in two-dimensional characters or one trick ponies. This has been really wonderful because this season, we get to see Raj really let go of his armor and evolve as a human being and be vulnerable -- which is rare for him."

"It's interesting how things have changed and it's incredible to think what this show has done over these past few years; it's amazing," Kaley Cuoco, who plays Penny, told THR.

The Big Bang Theory's Howard Wolowitz, Simon Helberg, teased fans something unprecedented is going to happen in the finale. "People are scared, people are threatened, people are jealous, and there's a lot to deal with," he told Screencrush.com, adding, "There's also something that's pretty unprecedented in the finale that we have not seen yet in all of the past seasons, so it's pretty exciting."

Something similar happened on TBBT Season 1: Raj is unaware he's drinking some placebo mix, and the gang listens to him talk to Penny about dating a girl from his home country. Realizing he's not under any influence of alcohol, Raj chickens out. Fast forward to Season 6, there is no more stopping Raj from talking to the ladies!

More 'The Big Bang Theory Season 6 Finale' Features:
Big Bang Theory Season 6 Finale Spoilers: 'Wolowitz' Actor Dishes Scoop, Teasers, and Some Shockers [VIDEOS]
The Big Bang Theory Season 6 Finale Spoilers: Leonard and Penny goes back to a Season 2 moment, Sheldon gets jealous! [READ]