Not all increase in prices can be attributed to inflation, especially so when the demand of goods increases due to speculation. Speculation involves the trading of a financial instrument involving high risk, in expectation of significant returns, taking maximum advantage from fluctuations in the market. Speculation causes a bubble to form, whereby the trading assets are trading at prices that strongly exceeds the asset’s intrinsic value.
A prime example is the subprime mortgage crisis in July / August 2007 whereby low-quality subprime loans were given to NINJAs (no income, no job, no assets). Anyone could get a housing loan with minimal interest rate, and this caused the prices of houses to skyrocket. Soon after, defaults on these NINJA loans caused the subprime mortgage crisis. The problem of a bubble is that it depends on an ever-increasing number of buyers, each person is betting on selling the asset to the next buyer at a higher price, eventually, it comes to a point where the high price cannot be justified and leads to the bubble bursting.