tipping point

noun

1. the point at which an issue, idea, product, etc., crosses a certain threshhold and gains significant momentum, triggered by some minor factor or change.
2. the point in a situation at which a minor development precipitates a crisis: Every infected person brings us closer to the tipping point, when the outbreak becomes an epidemic.
3. Physics. the point at which an object is no longer balanced, and adding a small amount of weight can cause it to topple.

noun

1. the crisis stage in a process, when a significant change takes place