2nd Edition Player's Handbook, p.85
Note that in 2nd Ed you had to declare your action before rolling initiative for the round, so the spellcaster doesn't even get to see whether their initiative check was any good before deciding to cast, and they lose their Dex bonus to AC making them even easier to hit. And also note that any failed save causes the spell to fizzle, meaning that it was possible to cause them to lose their spell by casting Know Alignment on them.
KarinsDad said:Apples and oranges. The vast majority of spell interruption in earlier editions was at the time of casting (a very limited window of time), not every single point in time after the spell is cast (a very wide window of time).
...some stuff

My current campaign has a wild magic sorcerer, and her player and I agreed that this, along with natural 1s on spell attacks and opponents rolling natural 20s on saves against her spells, will trigger her wild magic surges.We've long used a houserule that if a spell ends because you lost concentration, you roll on the Wild Magic table for a mishap. It's made for some really interesting (and memorable) battle scenes.
Welcome to the forums, @Kmetzker !
Our house rule is to allow multiple concentration spells but each with different targets, which allows most strategic play without cheesing buffing:I recently put together a Paladin for 5E and noticed that many of the spells requires Concentration.
I get the whole "prevent massive buffing" reasons for the rule, but I think that WotC went overboard with that.
I might add a house rule that allows multiple concentration spells, but increases the DC by 2 for each spell the caster is concentrating on if hit.
Two concentration spells up? Make two DC 12 (or half damage +2) concentration checks, one for each spell.
Three concentration spells up? Make three DC 14 (or half damage +4) concentration checks, one for each spell.
Yes, this type of house rule shifts the balance of power to casters a bit, but I basically figure that everyone and his brother is a caster in 5E anyway, might as well help most everyone out. Pros and Cons to this as well (i.e. one attack can take out multiple spells, this results in PCs casting more spells and having fewer for later, etc.).
Can anyone think of an alternative house rule that might work too?

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.