Learn Turkish: Oda boğulacak kadar kalabalık. - The room is crowded enough to suffocate in.

The pattern -(y)AcAk kadar means "to the point of doing [verb]" or "enough to [verb]". Here, it attaches to the verb boğulmak (to suffocate). Literally, it translates to "as much as one will suffocate". When placed before an adjective like kalabalık (crowded), it describes how crowded the room is.

Why is the verb boğulacak instead of boğacak?

The root verb is boğmak, which means "to choke" or "to strangle" someone else. By adding the passive suffix -ul, it becomes boğulmak, meaning "to be choked" or "to suffocate". Since we are talking about a general feeling of suffocating rather than someone actively choking a specific person, the passive form is used.

Why is there no personal ending on boğulacak? Who is suffocating?

There is no personal ending because this is a general statement. It means the room is crowded enough for anyone to suffocate in. If you wanted to say it was crowded enough for us to suffocate, you would add a possessive ending to the participle: boğulacağımız kadar. Without it, the phrase applies generally.

Why is the adjective kalabalık at the very end of the sentence?

In Turkish, the main predicate goes at the end. Here, kalabalık (crowded) is the predicate of the sentence (meaning "The room is crowded"). The phrase boğulacak kadar acts as an adverb describing the degree of the crowding, so it must be placed directly before the adjective it modifies.