What dramatic climax occurs toward the end of Act 1?

At the end of the first act, the 8th and 3rd Jurors get into a physical altercation. As the jury struggles to prove and experiment with timelines, the 3rd Juror reacts violently, calling their experimentation dishonest and saying that this kid had “got to burn.” The 8th Juror responds by calling 3rd Juror a “self-appointed public avenger” and a “sadist.” With this, the 3rd Juror leaps at him. Restrained by the other men, he shouts, “God damn it! I’ll kill him! I’ll kill him.” 8th Juror asks, “You don’t really mean you’ll kill me, do you?” proving his earlier point about how people say, “I’ll kill you,” when they don’t really mean it.