what happened is

You put a bid on it for $180
The current price is $100 so your bid increases it to $110

Another person comes along as sees it at $110 and bids, but because you already bid $180 they don't know and you will automatically become the highest bidder again after ebay does a 2nd bid to up the amount. This continues until it hits your $180 limit.

That's all, happens all the time and it's nothing to worry about.