A curious conundrum can be described in a variety of ways depending on the situation. Some synonyms for curious could be intriguing, fascinating, or perplexing. Conundrum can be substituted with puzzle, enigma, or mystery. An unusual problem could be categorized as an anomaly or a perplexity. Similarly, a complex or difficult question might be described as a quandary or a dilemma. It all depends on the context and the tone of the conversation. Regardless of the word choice, a curious conundrum will always offer a unique challenge to those trying to solve it.