Have you found a book that you enjoyed so much that you read it in a single day, or even in a single sitting? Every page of words is a page of happiness, of learning, of beautiful language, and relatable experiences, and even if you decide to stop for a break, or have other obligations in the 'real world', you soon guiltily retreat back into the new-found world for just one more chapter -- and then just one more.
Many books fall into this category: The Lord of the Rings, of course, even on a second or third or fourth reading; Frank McCourt's biographical trilogy of Angela's Ashes, 'Tis, and Teacher Man; everything by Wilde, and some of Asimov's works, for example. For me, at any rate. I'm sure your list is different, and rightly so.
And then there are books that are the opposite. You don't want to finish them, because even happy endings are sad. Yes, there are always more books; yes, you can re-read books, but the experience of reading a book for the first time and having the realisation that this one is a special one slowly seep through you like the warmth of a spiked coffee on a frosty evening is all too rare. Of knowing that time will pass, and lots of it, before another discovery like this is made, but that just this one book will alter your life in a small way forever. You still want to devour these books; to tear through the pages as fast as your eyes and mind will allow, gaining the treasures within for your own, while also leaving them intact for the next reader. You want this just as much as you did for the other exceptional books, maybe even more, but - something makes you hold back. Something tells you to take this one slowly, to savour every moment of it, knowing it might be the last for a while.
Read the title.