The Once & Future Realms
Spells sustained via concentration are disrupted only then the caster decides to drop it, looses the ability to hold it active (unconsciousness, possible environmental factors, etc.), takes damage, casts another spell with the “Concentration” duration, or casts a spell with a cast time longer than one action (rituals etc.).
The DC to resist broken concentration is DC 10 or damage taken, whichever is higher. You may add your proficiency bonus to this check.