Hi Madonna:
I've got the long black and grey Reebok step. No, I don't hear any loud popping sound and I've had mine for about 4 years.
I really like my Reebok. I find it very stable and don't have to worry about the risers shifting when I'm stepping "hard", or that I'm not fitting them to the platform correctly. I had a Bollinger step that looks identical to The Step, but I gave it away to my sister after a few weeks. I just didn't feel safe because the platform kept on shifting on the risers. I also found it made far too much noise on impact (risers and platform clapping together). Maybe The Step is different - maybe the risers lock in more securely? The locking feature in the Reebok is a selling point for me.
Anyway, if you're thinking about purchasing a Reebok step, I really recommend it.
Patricia