How and why did the Nullification Crisis almost bring us to the brink of civil war?

The constitutional theory of nullification holds that individual states have the right to nullify, that is to say invalidate, a federal law on the grounds that it is unconstitutional. In practice, however, the theory has never been upheld by a federal court. Nonetheless, in the early nineteenth century, nullification seemed like a live option, and its contemplation by South Carolina precipitated a major constitutional crisis.
It all started with tariffs. Under the presidency of John Quincy Adams, a number of tariffs were introduced to protect American industry from being undercut by cheap foreign imports. Although the measures were widely welcomed in the more industrialized North, they were deeply resented in the South. Due to the imposition of tariffs, Southerners would now have to pay considerably more for imported goods they couldn't produce themselves.
When Andrew Jackson won the presidency in 1828, his fellow Southerners naturally assumed that the hated tariffs would be significantly reduced, if not scrapped altogether. However, when that didn't happen, Southern opinion was outrage at the Jackson Administration's inaction. Even Vice President John C. Calhoun, a native of South Carolina, was at odds with his administration's policy.
Jackson attempted to address these concerns by making some tariff reductions in 1832. But this was far too little, far too late for Calhoun, who resigned the Vice Presidency in December of that year. More ominously still, the new measures were woefully inadequate in appeasing the growing anger of the Southern states at what they saw as a betrayal of their economic interests by an administration they had previously supported.
A month before Calhoun's resignation, a specially convened convention was held in South Carolina, which declared the tariffs of both 1828 and 1832 unconstitutional and unenforceable in the state. Those attending the convention knew that the Ordinance of Nullification which they'd passed would be fiercely resisted by the federal government as it represented a clear challenge to its authority. Military preparations were then made by the state authorities to counter any armed incursions by federal troops.
The situation was tense and highly dangerous; it seemed as if the nation was on the brink of civil war. Both the federal government and the state of South Carolina believed they had the Constitution on their side and were prepared to fight if necessary to prove that they were right. Thankfully, armed conflict was averted by means of a timely concession. President Jackson enacted the Compromise Tariff of 1833, which South Carolina found acceptable. Although civil war had been avoided, it was a close call. And South Carolina's defiance proved to be an eerie portent of events to come in the very same state less than thirty years later.