Infinite Queue can be activated and deactivated by pressing the small gray button with the infinity symbol ∞ right to the progress bar or by pressing Q. When activated, the ∞ button will flash green. If you're lacking the resources to produce an item, it is not produced and automatically removed from the queue. Reaching the population limit will not deactivate the Infinite Queue - the building continues to produce new items as soon as the limit is increased.