It's not correct that an increase in home value increases your property tax. The town has a budget which then it divides by the sum of all property values, this gives a ratio that is the tax rate per property value.

In theory, your property went up 40%, if everyone else's did too then your taxes remain the same. You can see this by viewing the tax rate over time and seeing that it has declined (but again, that didn't lower the dollar amount you must pay, just the ratio of tax to property value.)