I have only one book I had to put down because I just. couldn't. do. it. anymore.
"The Book of Dave" by Will Self. It is written in Will Self's invented language. Some parts were brilliant, but I spent so much time having to decipher the book, I got frustrated and just stopped reading it.
https://www.amazon.com/Book-Dave-Novel-Will-Self/dp/1596913843If you like literary challenges, this is a book for you.