I find it's like the egg white before you cook it, especially when you empty the egg and there's that last glob of egg white that won't let go of the shell!
I've only just started to track ovulation, but I used the cheapo pee sticks from Amazon - about £5 for 30 last month. When I was sure it was nearly time (I've got a predictor app on my phone) I used the Clearblue digital tests too. Confusingly, the cheapo ones gave me a different LH surge day to the digital ones, but I'm going to keep testing for the next couple of months.
These tests only show that you're about to ovulate - great for predicting when to get busy, but they don't tell if you HAVE ovulated. Apparently taking your temperature every morning will show that. I haven't started that yet, trying from next AF.