N3
あまりに
So much...that, (Way) too...
友達の話があまりにもつまらなくて途中からほとんど聞いてなかった。
My friend's story was so boring that I stopped paying attention halfway.
Explanation
「あまりに」 means 'far too...': the degree goes beyond what is tolerable or reasonable, with a bad result: 「あまりに寒くて、眠れなかった」 (It was so cold that I couldn't sleep). In speech it is often 「あまりにも」, and 「あんまり」 is also used. It can be doubled with 「~すぎる」 for emphasis: 「あまりに危険すぎる」.
Mixed up with
Don't confuse it with 「あまり~ない」 ('not very'). 「あまりに」 is followed by a positive sentence and means 'too...'; 「あまり~ない」 is negative and means 'not very...'. One small difference, opposite meaning.
The common N2 pattern 「あまりの+noun+に」: 「あまりの驚きに声も出なかった」 (I was so shocked I couldn't make a sound).