smelly :S

No, it's not normal. I would make an appointment with his vet to get him seen. It could be just a simple UTI which they sometimes get when they don't drink enough water. The doctor may suggest that you try different water dishes away from his food & liter box. (in case you didn't already know, food & water should be kept in a different room than the liter box.) But also depending on your cats age, and what other ailments he may have, it could be the start of kidney failure. Which is what I'm going through with my cat right now.

Check his water dish and see if he is drinking enough water. If not, that would make his urine more concentrated and stronger smelling. It could be a sign of some kidney condition. If it continues, especially if your cat is getting along in life, you might want to take him to the vet for a checkup.